Month: May 2025

The magic ingredient for a butterfly event outdoors is warmth and sunshine and the weekend of the 17th and 18th of May provided this magic. Bright, unbroken sunshine and the temperature peaking at 24 and 25 Celsius allowed butterflies and day-flying moths to fly at any time during the day. Butterflies do not usually fly throughout the day.  They feed, rest, shelter, bask, mate and lay eggs as well as flying.

I was a little fearful that the prolonged fine weather might have brought an early closure to the flight period of the Pearl-bordered Fritillary but happily, this butterfly put in a great display, glowing deep orange in crystal Burren sunshine.

What is also key to the success of any outing is the people taking part.  The enthusiastic group on both days sparked the atmosphere nicely, adding to the excitement of being in beautiful habitats in sublime weather. At Fahee North we sampled the butterflies in a site containing calcareous grassland, limestone heath, exposed limestone pavement, humid/wet grassland/marsh and scrub. The adjoining site holds open scrub on limestone pavement with dry calcareous grassland. This site, which holds a holy well, has long been notable for its Pearl-bordered Fritillary population. It must be emphasised that the habitats are protected by Burrenbeo Trust volunteers controlling, but not eliminating scrub. 

Scrub is a vital part of the habitats and must be retained. The image below shows a larval nest of Small Eggar caterpillars on Blackthorn that is part of a patch of roadside scrub. This moth has been recorded in just 34 10 km squares since 2000, 15 of these are in or near the Burren.  We enjoyed observing the to-ing and fro-ing of the heat-excited caterpillars. In the hottest part of the day, most had retreated to the interior of their web.

We were delighted to see so many Marsh Fritillaries on the grassland and heath. This is the earliest I have seen them in the Burren. We have males skirmishing, briefly and the more sedate females keeping a discreet difference. These had mated already so the males were of no interest to the females who were preparing to lay their first and largest egg load or were flying with the freedom that comes with significant weight loss, feeding and maturing a second egg batch. Common Blues were lesser in number but showy, bringing their sky-blue shimmer to the scene. Small Heath bobbed about the fescue tussocks, flashing their bright orange uppersides at us.

We moved onto the limestone pavement and soon Pearl-bordered Fritillaries appeared. Some were caught and placed in jars to be admired and released. Several moths were netted. I saw my first-ever Burren Narrow-bordered Five-spot Burnet along with Six-spot and Transparent Burnets (known from just four counties, mainly in Clare), all symbols of pristine, undamaged habitats. A spectacular day-flier, the Wood Tiger, was also netted and displayed, to the delight of all. It is a beautiful species and is probably uncommon everywhere it still occurs. It is listed as Near Threatened and has not been recorded in 17 counties in the Republic of Ireland since 2000. Speckled Yellow, which looks like a butterfly was also sighted. It rarely poses for photographs, alas! It has not been reported from 20 counties on the island of Ireland. When you see it in abundance in the Burren, don’t take this for granted. The Dew moth was also a welcome sight. This gem has been returned from just three counties: Clare, Galway and Mayo. It is in good hands in the Burren, as long as its habitat is not molested.

Sunday meant a later start but we made the most of the additional time with some exploring the nearby Cahercommaun ring fort. The surrounding calcareous grassland and Hazel scrub are rich in butterflies. The easy exploration allowed by the Clooncoose Valley Green Road is one benefit. This is surely Ireland’s Butterfly Road. The traffic can be congested and casualties occur with the area’s predators knowing that rich pickings are available. We watched a Hairy Dragonfly pounce on a male Marsh Fritillary, carrying the hapless victim in its vice-grip jaws. A collective dismay engulfed the group. The road teemed with dragonflies, mostly Black-tailed Skimmer, Hairy Dragonfly and Four-spotted Chaser. 

One area adjoining the road, a clearing in the scrub, was being used as a lek site by Small Heath butterflies. Watching the males display to catch a lady’s eye was intriguing. This is the first time I have seen this behaviour in this pretty little butterfly. I netted both, showed one to the group and when released he returned to his lekking site to continue with his competitive display.

The road offers a route through a large area, from near the Gort road to Cahercommaun and some butterflies using this infrastructure do not breed along the route; Marsh Fritillary and Pearl-bordered Fritillary seem to use it to move through the area and seek mates.

The Pearl-bordered Fritillary occurs only in the Burren, occupying just ten 10 km squares, mainly in the east Burren, in open scrub on limestone. It was only discovered in 1922, in Clooncoose. It remains in place hopefully never to be removed.

Thanks to everyone who helped, including those who spotted and netted butterflies, moths and dragonflies and especially to the lady who baked me a cake, another magic ingredient!

The long days of bright sunshine during March and April accelerated the development of the Marsh Fritillary caterpillars. This warmth continues into May as I write (13 May) stimulating the early emergence of the adult Marsh Fritillary butterfly.

Our management work at Lullybeg Reserve during the winter has helped shorten development times by expanding areas receiving direct sunlight and making more food and habitat available to the caterpillars and the adults.  The pattern of bright sunny days and cool, even cold nights might have helped in another way.

The Marsh Fritillary caterpillar is infected by two wasps, Cotesia bignelli and Cotesia melitaearum. The latter species produces three generations, predating a single generation of caterpillars. The first generation attacks the first instar larvae in July and August, killing a percentage of these before pupating, emerging and attacking third or fourth instar caterpillars, spending winter within fourth instar larvae. These infected larvae are killed in spring and the adult wasps infect the final growth stages of the caterpillars. Losses can be so large that a population is wiped out. This removes both the butterfly and wasp from the breeding habitat.

However, in cool, sunny springs, the emergence of adult wasps from their pupae is delayed. The developing wasps cannot heat themselves within their pupae and may remain longer than usual in this state. Meanwhile, the spring larvae develop faster in cool, sunny weather and will pupate before many of the wasps have hatched. In this way, more Marsh Fritillaries survive to take flight. The wasp cannot infect eggs, pupae or adults, and they emerge out of synchronicity with their prey. This might have occurred this year.

However, some final-stage larvae were infected; this year I have observed several larvae feeding intermittently, without enthusiasm. These will not pupate. Their lives are being prolonged by their internal parasitoids which, if they pupated now, would emerge without any available larvae to attack. 

Their tactic therefore is to bite their way out of the caterpillar, usually at the end of May and spin dense white silk over their pupae to deliberately prolong their pupal phase until the next generation of Marsh Fritillary caterpillars are available for them to attack in mid to late July. The cycle then begins again.

Maintaining a large area of habitat makes extinction at the site level less likely.  Maintaining connections with nearby populations means re-population can occur if a site loses its population due to conditions that favour the wasp. 

These objectives are being achieved in the Lullymore and Lullybeg areas. The recording of fifty Marsh Fritillaries in Lullybeg on Monday 12 May is a fitting reward for the hard work controlling scrub and disturbing selected areas of the sward containing the foodplant to avoid Moor-grass overdominating.

The butterflies seen on 12 May, all males, were patrolling low over the area, seeking newly hatched females in need of a mate. They were occasionally inspected by Dingy Skippers, also enjoying an early, populous spring. Happy times!

Photos copyright J. Harding

An Atlas of Butterflies in Ireland 2010-2021 and the Handbook for the Irish Vegetation Classification was launched today at the Royal Irish Academy by the minister responsible for the National Parks and Wildlife Service, Christopher O’Sullivan TD, who described his ministerial brief as his ‘dream job.’ What follows is the speech made by Jesmond Harding on behalf of Butterfly Conservation Ireland.

Hello Everyone.

An Atlas of Butterflies in Ireland 2010-2021 maps the distribution of all thirty-five butterflies that occur in Ireland, comparing the pre-2010 distribution to the 2010-2021 period. It maps the distribution of each species at the 10km level and additional maps plot the distribution of three rare species at a finer resolution. The two identical-looking wood white butterflies are individually mapped, applying the results of laboratory analysis to confirm species identity.

The Atlas combines data from seven separate datasets applying different recoding methodologies that contributed 408,812 records. Accounts for our thirty-five species from 28 authors describe the appearance, habitat, ecology, distribution map and population status of each butterfly. Abundance trends are provided for the 15 commonest butterflies. Summary accounts and maps are presented for five vagrant species. The species accounts are supported by chapters on “History of Butterfly Recording in Ireland”, “Breeding Habitats for Ireland’s Butterflies”, “Background and Data Sources”, “The Changing Fortunes of Ireland’s Butterflies” and “Why are Some of Ireland’s Butterflies Declining?”.

On behalf of the three bodies that produced this Atlas, the National Biodiversity Data Centre, Butterfly Conservation Northern Ireland and Butterfly Conservation Ireland I want to express our thanks to all the butterfly recorders who have contributed butterfly records since 1900. The Atlas Steering Committee comprising Frank Smyth, Bob Aldwell, John O’Boyle, Mary Foley, Liam Lysaght and I provided key advice and guidance to develop the Atlas content and performed record verification. Tomás Murray, then Senior Ecology at the National Biodiversity Data Centre worked to recruit and train volunteers and on Atlas design. Enormous credit is due to our 28 Atlas authors and the species accounts editing team Pat Bell, Richella Duggan, Jim Fitzharris, Liam Lysaght, and I. Brian Nelson provided important advice that added significantly to text clarity and accuracy. Dave Manser of Vitamin did an excellent job designing the publication. Having been involved in the Atlas from the outset, I can confidently say that nothing Liam or I asked contributors to do was too much. A heartfelt thanks is due for everyone’s generosity.

This Atlas provides a baseline for future recording, but comparing the 2010-2021 period with the 1900-2009 period also offers a glimpse into the status of our populations in the past. In 1995 Daniel Pauly, a fisheries expert coined the term ‘shifting baseline syndrome’ to describe the acceptance of degraded natural ecosystems. Pauly knew that fisheries experts evaluated depleted fish stocks by taking as their baseline the state of fisheries at the start of their careers rather than fish populations in their natural state. In this way, each new generation redefines what is ‘natural’. What we see now or in the recent past is interpreted as the natural state of populations, prompting pre-baseline amnesia. Future generations of butterfly recorders in Ireland taking the 2010-2021 period as their baseline comparator should be less prone to pre-baseline amnesia.

However, given the limited recording carried out, especially before the mid-1990s, contemporary recorders recruited during the Atlas period might take what they see as natural. It is not. Even our commonest butterflies are suffering the assault of modernity. The figures are chilling. The Orange-tip, our loveliest spring butterfly, has declined by -68% during 2008-2021 and lost more than 10% of its distribution since the 1995-2009 period. The other common whites are showing benumbing losses: Large White – 76%, Small White – 77% and Green-veined White -87.2%. The Atlas tells us that only one species, the Holly Blue, has shown an increase in population size during 2010-2021. For the 15 commonest species, the average decline during 2010-2021 is -55.35%. The highest decline, -88% afflicts the Ringlet, a quiet inhabitant of tall, humid grassland. More alarmingly, the Hedge Brown/Gatekeeper, its deep orange uppersides glowing against the deep-green mid-summer shrubbery has lost 40% of the distribution it held before 2010, falling from an occupancy of 99 10 km squares to 59.

None of these butterflies are highly specialised species that only occupy rare habitats. The reasons for the declines are described in the Atlas. We need to be on high alert when our commonest species plunge so precipitously because it speaks to widescale environmental degradation.

The deeper solutions require societal change but at a minimum avoiding the destruction of the remaining natural vegetation on public land would help. In this regard, draining state-owned bogs to install wind turbines, Waterways Ireland rock armouring the banks of the River Barrow and removing the river’s riparian vegetation, applying herbicide in public parks to kill nettles and removing hedges and roadside trees are readily avoidable.

Beyond this, assiduous application of the EU Nature Restoration Law, protecting habitats at the landscape level, including creating a National Park on state-owned peatlands in northwest Kildare/East Offaly, will be a declaration of real intent.

The issue of chemically mediated agriculture must be addressed. Intensive farming damages our entire environment by polluting soils, water, and the atmosphere. Our butterflies are suffering from these pollution impacts. Butterflies are conspicuous and easily recordable, making them among the most reliable biological indicators we have. They indicate the quality of the soil, water, air, and vegetation.

Butterflies are the proverbial canary in the coal mine. The canary must not stop singing. If it does, we might not be around to see the results.

Thank you.

Ends

Some Key points from the Atlas

Of the resident species recorded:

16 showed no significant change in distribution.

Seven species increased in their range, with the Comma butterfly showing the largest expansion in range since it was first recorded in Wexford in 2000. It is now common in the southern part of the country. This is considered a natural expansion due to climate change. The others, from the largest expansion to the lowest, are Essex Skipper, Small Skipper, Marsh Fritillary, Holly Blue, Dingy Skipper, and Silver-washed Fritillary.

Nine decreased in range with the most dramatic being that of Wall. The Wall was recorded in  52.20% fewer 10km squares in 2010-2021 and before 2010. It has died out from large parts of the midlands (especially the north midlands) and is becoming increasingly confined to coastal habitats. It is thought that this decline is the result of dual factors associated with excess nitrogen in the environment and a changing climate. 

The research shows that whilst changing environmental conditions results in more favourable habitat conditions for a small number of resident species, it primarily creates conditions that are less favourable, leading to the decline in many species of butterflies in Ireland.

The two publications are available to purchase online at the Biodiversity Ireland Shop. 

Further information: https://www.npws.ie/news/minister-o%E2%80%99sullivan-launches-two-landmark-publications-support-ireland%E2%80%99s-biodiversity-and